1d6d48196SJens Axboe /* 2d6d48196SJens Axboe * Functions related to segment and merge handling 3d6d48196SJens Axboe */ 4d6d48196SJens Axboe #include <linux/kernel.h> 5d6d48196SJens Axboe #include <linux/module.h> 6d6d48196SJens Axboe #include <linux/bio.h> 7d6d48196SJens Axboe #include <linux/blkdev.h> 8d6d48196SJens Axboe #include <linux/scatterlist.h> 9d6d48196SJens Axboe 10cda22646SMike Krinkin #include <trace/events/block.h> 11cda22646SMike Krinkin 12d6d48196SJens Axboe #include "blk.h" 13d6d48196SJens Axboe 1454efd50bSKent Overstreet static struct bio *blk_bio_discard_split(struct request_queue *q, 1554efd50bSKent Overstreet struct bio *bio, 16bdced438SMing Lei struct bio_set *bs, 17bdced438SMing Lei unsigned *nsegs) 1854efd50bSKent Overstreet { 1954efd50bSKent Overstreet unsigned int max_discard_sectors, granularity; 2054efd50bSKent Overstreet int alignment; 2154efd50bSKent Overstreet sector_t tmp; 2254efd50bSKent Overstreet unsigned split_sectors; 2354efd50bSKent Overstreet 24bdced438SMing Lei *nsegs = 1; 25bdced438SMing Lei 2654efd50bSKent Overstreet /* Zero-sector (unknown) and one-sector granularities are the same. */ 2754efd50bSKent Overstreet granularity = max(q->limits.discard_granularity >> 9, 1U); 2854efd50bSKent Overstreet 2954efd50bSKent Overstreet max_discard_sectors = min(q->limits.max_discard_sectors, UINT_MAX >> 9); 3054efd50bSKent Overstreet max_discard_sectors -= max_discard_sectors % granularity; 3154efd50bSKent Overstreet 3254efd50bSKent Overstreet if (unlikely(!max_discard_sectors)) { 3354efd50bSKent Overstreet /* XXX: warn */ 3454efd50bSKent Overstreet return NULL; 3554efd50bSKent Overstreet } 3654efd50bSKent Overstreet 3754efd50bSKent Overstreet if (bio_sectors(bio) <= max_discard_sectors) 3854efd50bSKent Overstreet return NULL; 3954efd50bSKent Overstreet 4054efd50bSKent Overstreet split_sectors = max_discard_sectors; 4154efd50bSKent Overstreet 4254efd50bSKent Overstreet /* 4354efd50bSKent Overstreet * If the next starting sector would be misaligned, stop the discard at 4454efd50bSKent Overstreet * the previous aligned sector. 4554efd50bSKent Overstreet */ 4654efd50bSKent Overstreet alignment = (q->limits.discard_alignment >> 9) % granularity; 4754efd50bSKent Overstreet 4854efd50bSKent Overstreet tmp = bio->bi_iter.bi_sector + split_sectors - alignment; 4954efd50bSKent Overstreet tmp = sector_div(tmp, granularity); 5054efd50bSKent Overstreet 5154efd50bSKent Overstreet if (split_sectors > tmp) 5254efd50bSKent Overstreet split_sectors -= tmp; 5354efd50bSKent Overstreet 5454efd50bSKent Overstreet return bio_split(bio, split_sectors, GFP_NOIO, bs); 5554efd50bSKent Overstreet } 5654efd50bSKent Overstreet 57885fa13fSChristoph Hellwig static struct bio *blk_bio_write_zeroes_split(struct request_queue *q, 58885fa13fSChristoph Hellwig struct bio *bio, struct bio_set *bs, unsigned *nsegs) 59885fa13fSChristoph Hellwig { 60885fa13fSChristoph Hellwig *nsegs = 1; 61885fa13fSChristoph Hellwig 62885fa13fSChristoph Hellwig if (!q->limits.max_write_zeroes_sectors) 63885fa13fSChristoph Hellwig return NULL; 64885fa13fSChristoph Hellwig 65885fa13fSChristoph Hellwig if (bio_sectors(bio) <= q->limits.max_write_zeroes_sectors) 66885fa13fSChristoph Hellwig return NULL; 67885fa13fSChristoph Hellwig 68885fa13fSChristoph Hellwig return bio_split(bio, q->limits.max_write_zeroes_sectors, GFP_NOIO, bs); 69885fa13fSChristoph Hellwig } 70885fa13fSChristoph Hellwig 7154efd50bSKent Overstreet static struct bio *blk_bio_write_same_split(struct request_queue *q, 7254efd50bSKent Overstreet struct bio *bio, 73bdced438SMing Lei struct bio_set *bs, 74bdced438SMing Lei unsigned *nsegs) 7554efd50bSKent Overstreet { 76bdced438SMing Lei *nsegs = 1; 77bdced438SMing Lei 7854efd50bSKent Overstreet if (!q->limits.max_write_same_sectors) 7954efd50bSKent Overstreet return NULL; 8054efd50bSKent Overstreet 8154efd50bSKent Overstreet if (bio_sectors(bio) <= q->limits.max_write_same_sectors) 8254efd50bSKent Overstreet return NULL; 8354efd50bSKent Overstreet 8454efd50bSKent Overstreet return bio_split(bio, q->limits.max_write_same_sectors, GFP_NOIO, bs); 8554efd50bSKent Overstreet } 8654efd50bSKent Overstreet 87d0e5fbb0SMing Lei static inline unsigned get_max_io_size(struct request_queue *q, 88d0e5fbb0SMing Lei struct bio *bio) 89d0e5fbb0SMing Lei { 90d0e5fbb0SMing Lei unsigned sectors = blk_max_size_offset(q, bio->bi_iter.bi_sector); 91d0e5fbb0SMing Lei unsigned mask = queue_logical_block_size(q) - 1; 92d0e5fbb0SMing Lei 93d0e5fbb0SMing Lei /* aligned to logical block size */ 94d0e5fbb0SMing Lei sectors &= ~(mask >> 9); 95d0e5fbb0SMing Lei 96d0e5fbb0SMing Lei return sectors; 97d0e5fbb0SMing Lei } 98d0e5fbb0SMing Lei 9954efd50bSKent Overstreet static struct bio *blk_bio_segment_split(struct request_queue *q, 10054efd50bSKent Overstreet struct bio *bio, 101bdced438SMing Lei struct bio_set *bs, 102bdced438SMing Lei unsigned *segs) 10354efd50bSKent Overstreet { 1045014c311SJens Axboe struct bio_vec bv, bvprv, *bvprvp = NULL; 10554efd50bSKent Overstreet struct bvec_iter iter; 1068ae12666SKent Overstreet unsigned seg_size = 0, nsegs = 0, sectors = 0; 10702e70742SMing Lei unsigned front_seg_size = bio->bi_seg_front_size; 10802e70742SMing Lei bool do_split = true; 10902e70742SMing Lei struct bio *new = NULL; 110d0e5fbb0SMing Lei const unsigned max_sectors = get_max_io_size(q, bio); 1114d70dca4SMing Lei unsigned bvecs = 0; 11254efd50bSKent Overstreet 11354efd50bSKent Overstreet bio_for_each_segment(bv, bio, iter) { 11454efd50bSKent Overstreet /* 1154d70dca4SMing Lei * With arbitrary bio size, the incoming bio may be very 1164d70dca4SMing Lei * big. We have to split the bio into small bios so that 1174d70dca4SMing Lei * each holds at most BIO_MAX_PAGES bvecs because 1184d70dca4SMing Lei * bio_clone() can fail to allocate big bvecs. 1194d70dca4SMing Lei * 1204d70dca4SMing Lei * It should have been better to apply the limit per 1214d70dca4SMing Lei * request queue in which bio_clone() is involved, 1224d70dca4SMing Lei * instead of globally. The biggest blocker is the 1234d70dca4SMing Lei * bio_clone() in bio bounce. 1244d70dca4SMing Lei * 1254d70dca4SMing Lei * If bio is splitted by this reason, we should have 1264d70dca4SMing Lei * allowed to continue bios merging, but don't do 1274d70dca4SMing Lei * that now for making the change simple. 1284d70dca4SMing Lei * 1294d70dca4SMing Lei * TODO: deal with bio bounce's bio_clone() gracefully 1304d70dca4SMing Lei * and convert the global limit into per-queue limit. 1314d70dca4SMing Lei */ 1324d70dca4SMing Lei if (bvecs++ >= BIO_MAX_PAGES) 1334d70dca4SMing Lei goto split; 1344d70dca4SMing Lei 1354d70dca4SMing Lei /* 13654efd50bSKent Overstreet * If the queue doesn't support SG gaps and adding this 13754efd50bSKent Overstreet * offset would create a gap, disallow it. 13854efd50bSKent Overstreet */ 1395014c311SJens Axboe if (bvprvp && bvec_gap_to_prev(q, bvprvp, bv.bv_offset)) 14054efd50bSKent Overstreet goto split; 14154efd50bSKent Overstreet 142d0e5fbb0SMing Lei if (sectors + (bv.bv_len >> 9) > max_sectors) { 143e36f6204SKeith Busch /* 144e36f6204SKeith Busch * Consider this a new segment if we're splitting in 145e36f6204SKeith Busch * the middle of this vector. 146e36f6204SKeith Busch */ 147e36f6204SKeith Busch if (nsegs < queue_max_segments(q) && 148d0e5fbb0SMing Lei sectors < max_sectors) { 149e36f6204SKeith Busch nsegs++; 150d0e5fbb0SMing Lei sectors = max_sectors; 151e36f6204SKeith Busch } 152d0e5fbb0SMing Lei if (sectors) 153e36f6204SKeith Busch goto split; 154d0e5fbb0SMing Lei /* Make this single bvec as the 1st segment */ 155e36f6204SKeith Busch } 156e36f6204SKeith Busch 1575014c311SJens Axboe if (bvprvp && blk_queue_cluster(q)) { 15854efd50bSKent Overstreet if (seg_size + bv.bv_len > queue_max_segment_size(q)) 15954efd50bSKent Overstreet goto new_segment; 1605014c311SJens Axboe if (!BIOVEC_PHYS_MERGEABLE(bvprvp, &bv)) 16154efd50bSKent Overstreet goto new_segment; 1625014c311SJens Axboe if (!BIOVEC_SEG_BOUNDARY(q, bvprvp, &bv)) 16354efd50bSKent Overstreet goto new_segment; 16454efd50bSKent Overstreet 16554efd50bSKent Overstreet seg_size += bv.bv_len; 16654efd50bSKent Overstreet bvprv = bv; 167578270bfSMing Lei bvprvp = &bvprv; 16852cc6eeaSMing Lei sectors += bv.bv_len >> 9; 169a88d32afSMing Lei 170a88d32afSMing Lei if (nsegs == 1 && seg_size > front_seg_size) 171a88d32afSMing Lei front_seg_size = seg_size; 17254efd50bSKent Overstreet continue; 17354efd50bSKent Overstreet } 17454efd50bSKent Overstreet new_segment: 17554efd50bSKent Overstreet if (nsegs == queue_max_segments(q)) 17654efd50bSKent Overstreet goto split; 17754efd50bSKent Overstreet 17854efd50bSKent Overstreet nsegs++; 17954efd50bSKent Overstreet bvprv = bv; 180578270bfSMing Lei bvprvp = &bvprv; 18154efd50bSKent Overstreet seg_size = bv.bv_len; 18252cc6eeaSMing Lei sectors += bv.bv_len >> 9; 18302e70742SMing Lei 18402e70742SMing Lei if (nsegs == 1 && seg_size > front_seg_size) 18502e70742SMing Lei front_seg_size = seg_size; 18654efd50bSKent Overstreet } 18754efd50bSKent Overstreet 18802e70742SMing Lei do_split = false; 18954efd50bSKent Overstreet split: 190bdced438SMing Lei *segs = nsegs; 19102e70742SMing Lei 19202e70742SMing Lei if (do_split) { 19302e70742SMing Lei new = bio_split(bio, sectors, GFP_NOIO, bs); 19402e70742SMing Lei if (new) 19502e70742SMing Lei bio = new; 19602e70742SMing Lei } 19702e70742SMing Lei 19802e70742SMing Lei bio->bi_seg_front_size = front_seg_size; 19902e70742SMing Lei if (seg_size > bio->bi_seg_back_size) 20002e70742SMing Lei bio->bi_seg_back_size = seg_size; 20102e70742SMing Lei 20202e70742SMing Lei return do_split ? new : NULL; 20354efd50bSKent Overstreet } 20454efd50bSKent Overstreet 205af67c31fSNeilBrown void blk_queue_split(struct request_queue *q, struct bio **bio) 20654efd50bSKent Overstreet { 207bdced438SMing Lei struct bio *split, *res; 208bdced438SMing Lei unsigned nsegs; 20954efd50bSKent Overstreet 2107afafc8aSAdrian Hunter switch (bio_op(*bio)) { 2117afafc8aSAdrian Hunter case REQ_OP_DISCARD: 2127afafc8aSAdrian Hunter case REQ_OP_SECURE_ERASE: 213af67c31fSNeilBrown split = blk_bio_discard_split(q, *bio, q->bio_split, &nsegs); 2147afafc8aSAdrian Hunter break; 215a6f0788eSChaitanya Kulkarni case REQ_OP_WRITE_ZEROES: 216af67c31fSNeilBrown split = blk_bio_write_zeroes_split(q, *bio, q->bio_split, &nsegs); 217a6f0788eSChaitanya Kulkarni break; 2187afafc8aSAdrian Hunter case REQ_OP_WRITE_SAME: 219af67c31fSNeilBrown split = blk_bio_write_same_split(q, *bio, q->bio_split, &nsegs); 2207afafc8aSAdrian Hunter break; 2217afafc8aSAdrian Hunter default: 222bdced438SMing Lei split = blk_bio_segment_split(q, *bio, q->bio_split, &nsegs); 2237afafc8aSAdrian Hunter break; 2247afafc8aSAdrian Hunter } 225bdced438SMing Lei 226bdced438SMing Lei /* physical segments can be figured out during splitting */ 227bdced438SMing Lei res = split ? split : *bio; 228bdced438SMing Lei res->bi_phys_segments = nsegs; 229bdced438SMing Lei bio_set_flag(res, BIO_SEG_VALID); 23054efd50bSKent Overstreet 23154efd50bSKent Overstreet if (split) { 2326ac45aebSMing Lei /* there isn't chance to merge the splitted bio */ 2331eff9d32SJens Axboe split->bi_opf |= REQ_NOMERGE; 2346ac45aebSMing Lei 23554efd50bSKent Overstreet bio_chain(split, *bio); 236cda22646SMike Krinkin trace_block_split(q, split, (*bio)->bi_iter.bi_sector); 23754efd50bSKent Overstreet generic_make_request(*bio); 23854efd50bSKent Overstreet *bio = split; 23954efd50bSKent Overstreet } 24054efd50bSKent Overstreet } 24154efd50bSKent Overstreet EXPORT_SYMBOL(blk_queue_split); 24254efd50bSKent Overstreet 2431e428079SJens Axboe static unsigned int __blk_recalc_rq_segments(struct request_queue *q, 24407388549SMing Lei struct bio *bio, 24507388549SMing Lei bool no_sg_merge) 246d6d48196SJens Axboe { 2477988613bSKent Overstreet struct bio_vec bv, bvprv = { NULL }; 24854efd50bSKent Overstreet int cluster, prev = 0; 2491e428079SJens Axboe unsigned int seg_size, nr_phys_segs; 25059247eaeSJens Axboe struct bio *fbio, *bbio; 2517988613bSKent Overstreet struct bvec_iter iter; 252d6d48196SJens Axboe 2531e428079SJens Axboe if (!bio) 2541e428079SJens Axboe return 0; 255d6d48196SJens Axboe 256a6f0788eSChaitanya Kulkarni switch (bio_op(bio)) { 257a6f0788eSChaitanya Kulkarni case REQ_OP_DISCARD: 258a6f0788eSChaitanya Kulkarni case REQ_OP_SECURE_ERASE: 259a6f0788eSChaitanya Kulkarni case REQ_OP_WRITE_ZEROES: 260f9d03f96SChristoph Hellwig return 0; 261f9d03f96SChristoph Hellwig case REQ_OP_WRITE_SAME: 2625cb8850cSKent Overstreet return 1; 263a6f0788eSChaitanya Kulkarni } 2645cb8850cSKent Overstreet 2651e428079SJens Axboe fbio = bio; 266e692cb66SMartin K. Petersen cluster = blk_queue_cluster(q); 2675df97b91SMikulas Patocka seg_size = 0; 2682c8919deSAndi Kleen nr_phys_segs = 0; 2691e428079SJens Axboe for_each_bio(bio) { 2707988613bSKent Overstreet bio_for_each_segment(bv, bio, iter) { 271d6d48196SJens Axboe /* 27205f1dd53SJens Axboe * If SG merging is disabled, each bio vector is 27305f1dd53SJens Axboe * a segment 27405f1dd53SJens Axboe */ 27505f1dd53SJens Axboe if (no_sg_merge) 27605f1dd53SJens Axboe goto new_segment; 27705f1dd53SJens Axboe 27854efd50bSKent Overstreet if (prev && cluster) { 2797988613bSKent Overstreet if (seg_size + bv.bv_len 280ae03bf63SMartin K. Petersen > queue_max_segment_size(q)) 281d6d48196SJens Axboe goto new_segment; 2827988613bSKent Overstreet if (!BIOVEC_PHYS_MERGEABLE(&bvprv, &bv)) 283d6d48196SJens Axboe goto new_segment; 2847988613bSKent Overstreet if (!BIOVEC_SEG_BOUNDARY(q, &bvprv, &bv)) 285d6d48196SJens Axboe goto new_segment; 286d6d48196SJens Axboe 2877988613bSKent Overstreet seg_size += bv.bv_len; 288d6d48196SJens Axboe bvprv = bv; 289d6d48196SJens Axboe continue; 290d6d48196SJens Axboe } 291d6d48196SJens Axboe new_segment: 2921e428079SJens Axboe if (nr_phys_segs == 1 && seg_size > 2931e428079SJens Axboe fbio->bi_seg_front_size) 2941e428079SJens Axboe fbio->bi_seg_front_size = seg_size; 29586771427SFUJITA Tomonori 296d6d48196SJens Axboe nr_phys_segs++; 297d6d48196SJens Axboe bvprv = bv; 29854efd50bSKent Overstreet prev = 1; 2997988613bSKent Overstreet seg_size = bv.bv_len; 300d6d48196SJens Axboe } 30159247eaeSJens Axboe bbio = bio; 3021e428079SJens Axboe } 303d6d48196SJens Axboe 30459247eaeSJens Axboe if (nr_phys_segs == 1 && seg_size > fbio->bi_seg_front_size) 30559247eaeSJens Axboe fbio->bi_seg_front_size = seg_size; 30659247eaeSJens Axboe if (seg_size > bbio->bi_seg_back_size) 30759247eaeSJens Axboe bbio->bi_seg_back_size = seg_size; 3081e428079SJens Axboe 3091e428079SJens Axboe return nr_phys_segs; 3101e428079SJens Axboe } 3111e428079SJens Axboe 3121e428079SJens Axboe void blk_recalc_rq_segments(struct request *rq) 3131e428079SJens Axboe { 31407388549SMing Lei bool no_sg_merge = !!test_bit(QUEUE_FLAG_NO_SG_MERGE, 31507388549SMing Lei &rq->q->queue_flags); 31607388549SMing Lei 31707388549SMing Lei rq->nr_phys_segments = __blk_recalc_rq_segments(rq->q, rq->bio, 31807388549SMing Lei no_sg_merge); 319d6d48196SJens Axboe } 320d6d48196SJens Axboe 321d6d48196SJens Axboe void blk_recount_segments(struct request_queue *q, struct bio *bio) 322d6d48196SJens Axboe { 3237f60dcaaSMing Lei unsigned short seg_cnt; 324764f612cSMing Lei 3257f60dcaaSMing Lei /* estimate segment number by bi_vcnt for non-cloned bio */ 3267f60dcaaSMing Lei if (bio_flagged(bio, BIO_CLONED)) 3277f60dcaaSMing Lei seg_cnt = bio_segments(bio); 3287f60dcaaSMing Lei else 3297f60dcaaSMing Lei seg_cnt = bio->bi_vcnt; 3307f60dcaaSMing Lei 3317f60dcaaSMing Lei if (test_bit(QUEUE_FLAG_NO_SG_MERGE, &q->queue_flags) && 3327f60dcaaSMing Lei (seg_cnt < queue_max_segments(q))) 3337f60dcaaSMing Lei bio->bi_phys_segments = seg_cnt; 33405f1dd53SJens Axboe else { 335d6d48196SJens Axboe struct bio *nxt = bio->bi_next; 3361e428079SJens Axboe 337d6d48196SJens Axboe bio->bi_next = NULL; 3387f60dcaaSMing Lei bio->bi_phys_segments = __blk_recalc_rq_segments(q, bio, false); 339d6d48196SJens Axboe bio->bi_next = nxt; 34005f1dd53SJens Axboe } 34105f1dd53SJens Axboe 342b7c44ed9SJens Axboe bio_set_flag(bio, BIO_SEG_VALID); 343d6d48196SJens Axboe } 344d6d48196SJens Axboe EXPORT_SYMBOL(blk_recount_segments); 345d6d48196SJens Axboe 346d6d48196SJens Axboe static int blk_phys_contig_segment(struct request_queue *q, struct bio *bio, 347d6d48196SJens Axboe struct bio *nxt) 348d6d48196SJens Axboe { 3492b8221e1SKent Overstreet struct bio_vec end_bv = { NULL }, nxt_bv; 350f619d254SKent Overstreet 351e692cb66SMartin K. Petersen if (!blk_queue_cluster(q)) 352d6d48196SJens Axboe return 0; 353d6d48196SJens Axboe 35486771427SFUJITA Tomonori if (bio->bi_seg_back_size + nxt->bi_seg_front_size > 355ae03bf63SMartin K. Petersen queue_max_segment_size(q)) 356d6d48196SJens Axboe return 0; 357d6d48196SJens Axboe 358e17fc0a1SDavid Woodhouse if (!bio_has_data(bio)) 359e17fc0a1SDavid Woodhouse return 1; 360e17fc0a1SDavid Woodhouse 361e827091cSMing Lei bio_get_last_bvec(bio, &end_bv); 362e827091cSMing Lei bio_get_first_bvec(nxt, &nxt_bv); 363f619d254SKent Overstreet 364f619d254SKent Overstreet if (!BIOVEC_PHYS_MERGEABLE(&end_bv, &nxt_bv)) 365e17fc0a1SDavid Woodhouse return 0; 366e17fc0a1SDavid Woodhouse 367d6d48196SJens Axboe /* 368e17fc0a1SDavid Woodhouse * bio and nxt are contiguous in memory; check if the queue allows 369d6d48196SJens Axboe * these two to be merged into one 370d6d48196SJens Axboe */ 371f619d254SKent Overstreet if (BIOVEC_SEG_BOUNDARY(q, &end_bv, &nxt_bv)) 372d6d48196SJens Axboe return 1; 373d6d48196SJens Axboe 374d6d48196SJens Axboe return 0; 375d6d48196SJens Axboe } 376d6d48196SJens Axboe 3777988613bSKent Overstreet static inline void 378963ab9e5SAsias He __blk_segment_map_sg(struct request_queue *q, struct bio_vec *bvec, 3797988613bSKent Overstreet struct scatterlist *sglist, struct bio_vec *bvprv, 380963ab9e5SAsias He struct scatterlist **sg, int *nsegs, int *cluster) 381963ab9e5SAsias He { 382963ab9e5SAsias He 383963ab9e5SAsias He int nbytes = bvec->bv_len; 384963ab9e5SAsias He 3857988613bSKent Overstreet if (*sg && *cluster) { 386963ab9e5SAsias He if ((*sg)->length + nbytes > queue_max_segment_size(q)) 387963ab9e5SAsias He goto new_segment; 388963ab9e5SAsias He 3897988613bSKent Overstreet if (!BIOVEC_PHYS_MERGEABLE(bvprv, bvec)) 390963ab9e5SAsias He goto new_segment; 3917988613bSKent Overstreet if (!BIOVEC_SEG_BOUNDARY(q, bvprv, bvec)) 392963ab9e5SAsias He goto new_segment; 393963ab9e5SAsias He 394963ab9e5SAsias He (*sg)->length += nbytes; 395963ab9e5SAsias He } else { 396963ab9e5SAsias He new_segment: 397963ab9e5SAsias He if (!*sg) 398963ab9e5SAsias He *sg = sglist; 399963ab9e5SAsias He else { 400963ab9e5SAsias He /* 401963ab9e5SAsias He * If the driver previously mapped a shorter 402963ab9e5SAsias He * list, we could see a termination bit 403963ab9e5SAsias He * prematurely unless it fully inits the sg 404963ab9e5SAsias He * table on each mapping. We KNOW that there 405963ab9e5SAsias He * must be more entries here or the driver 406963ab9e5SAsias He * would be buggy, so force clear the 407963ab9e5SAsias He * termination bit to avoid doing a full 408963ab9e5SAsias He * sg_init_table() in drivers for each command. 409963ab9e5SAsias He */ 410c8164d89SPaolo Bonzini sg_unmark_end(*sg); 411963ab9e5SAsias He *sg = sg_next(*sg); 412963ab9e5SAsias He } 413963ab9e5SAsias He 414963ab9e5SAsias He sg_set_page(*sg, bvec->bv_page, nbytes, bvec->bv_offset); 415963ab9e5SAsias He (*nsegs)++; 416963ab9e5SAsias He } 4177988613bSKent Overstreet *bvprv = *bvec; 418963ab9e5SAsias He } 419963ab9e5SAsias He 420f9d03f96SChristoph Hellwig static inline int __blk_bvec_map_sg(struct request_queue *q, struct bio_vec bv, 421f9d03f96SChristoph Hellwig struct scatterlist *sglist, struct scatterlist **sg) 422f9d03f96SChristoph Hellwig { 423f9d03f96SChristoph Hellwig *sg = sglist; 424f9d03f96SChristoph Hellwig sg_set_page(*sg, bv.bv_page, bv.bv_len, bv.bv_offset); 425f9d03f96SChristoph Hellwig return 1; 426f9d03f96SChristoph Hellwig } 427f9d03f96SChristoph Hellwig 4285cb8850cSKent Overstreet static int __blk_bios_map_sg(struct request_queue *q, struct bio *bio, 4295cb8850cSKent Overstreet struct scatterlist *sglist, 4305cb8850cSKent Overstreet struct scatterlist **sg) 4315cb8850cSKent Overstreet { 4325cb8850cSKent Overstreet struct bio_vec bvec, bvprv = { NULL }; 4335cb8850cSKent Overstreet struct bvec_iter iter; 434f9d03f96SChristoph Hellwig int cluster = blk_queue_cluster(q), nsegs = 0; 4355cb8850cSKent Overstreet 4365cb8850cSKent Overstreet for_each_bio(bio) 4375cb8850cSKent Overstreet bio_for_each_segment(bvec, bio, iter) 4385cb8850cSKent Overstreet __blk_segment_map_sg(q, &bvec, sglist, &bvprv, sg, 4395cb8850cSKent Overstreet &nsegs, &cluster); 4405cb8850cSKent Overstreet 4415cb8850cSKent Overstreet return nsegs; 4425cb8850cSKent Overstreet } 4435cb8850cSKent Overstreet 444d6d48196SJens Axboe /* 445d6d48196SJens Axboe * map a request to scatterlist, return number of sg entries setup. Caller 446d6d48196SJens Axboe * must make sure sg can hold rq->nr_phys_segments entries 447d6d48196SJens Axboe */ 448d6d48196SJens Axboe int blk_rq_map_sg(struct request_queue *q, struct request *rq, 449d6d48196SJens Axboe struct scatterlist *sglist) 450d6d48196SJens Axboe { 4515cb8850cSKent Overstreet struct scatterlist *sg = NULL; 4525cb8850cSKent Overstreet int nsegs = 0; 453d6d48196SJens Axboe 454f9d03f96SChristoph Hellwig if (rq->rq_flags & RQF_SPECIAL_PAYLOAD) 455f9d03f96SChristoph Hellwig nsegs = __blk_bvec_map_sg(q, rq->special_vec, sglist, &sg); 456f9d03f96SChristoph Hellwig else if (rq->bio && bio_op(rq->bio) == REQ_OP_WRITE_SAME) 457f9d03f96SChristoph Hellwig nsegs = __blk_bvec_map_sg(q, bio_iovec(rq->bio), sglist, &sg); 458f9d03f96SChristoph Hellwig else if (rq->bio) 4595cb8850cSKent Overstreet nsegs = __blk_bios_map_sg(q, rq->bio, sglist, &sg); 460f18573abSFUJITA Tomonori 461e8064021SChristoph Hellwig if (unlikely(rq->rq_flags & RQF_COPY_USER) && 4622e46e8b2STejun Heo (blk_rq_bytes(rq) & q->dma_pad_mask)) { 4632e46e8b2STejun Heo unsigned int pad_len = 4642e46e8b2STejun Heo (q->dma_pad_mask & ~blk_rq_bytes(rq)) + 1; 465f18573abSFUJITA Tomonori 466f18573abSFUJITA Tomonori sg->length += pad_len; 467f18573abSFUJITA Tomonori rq->extra_len += pad_len; 468f18573abSFUJITA Tomonori } 469f18573abSFUJITA Tomonori 4702fb98e84STejun Heo if (q->dma_drain_size && q->dma_drain_needed(rq)) { 471a8ebb056SMike Christie if (op_is_write(req_op(rq))) 472db0a2e00STejun Heo memset(q->dma_drain_buffer, 0, q->dma_drain_size); 473db0a2e00STejun Heo 474da81ed16SDan Williams sg_unmark_end(sg); 475d6d48196SJens Axboe sg = sg_next(sg); 476d6d48196SJens Axboe sg_set_page(sg, virt_to_page(q->dma_drain_buffer), 477d6d48196SJens Axboe q->dma_drain_size, 478d6d48196SJens Axboe ((unsigned long)q->dma_drain_buffer) & 479d6d48196SJens Axboe (PAGE_SIZE - 1)); 480d6d48196SJens Axboe nsegs++; 4817a85f889SFUJITA Tomonori rq->extra_len += q->dma_drain_size; 482d6d48196SJens Axboe } 483d6d48196SJens Axboe 484d6d48196SJens Axboe if (sg) 485d6d48196SJens Axboe sg_mark_end(sg); 486d6d48196SJens Axboe 48712e57f59SMing Lei /* 48812e57f59SMing Lei * Something must have been wrong if the figured number of 48912e57f59SMing Lei * segment is bigger than number of req's physical segments 49012e57f59SMing Lei */ 491f9d03f96SChristoph Hellwig WARN_ON(nsegs > blk_rq_nr_phys_segments(rq)); 49212e57f59SMing Lei 493d6d48196SJens Axboe return nsegs; 494d6d48196SJens Axboe } 495d6d48196SJens Axboe EXPORT_SYMBOL(blk_rq_map_sg); 496d6d48196SJens Axboe 497d6d48196SJens Axboe static inline int ll_new_hw_segment(struct request_queue *q, 498d6d48196SJens Axboe struct request *req, 499d6d48196SJens Axboe struct bio *bio) 500d6d48196SJens Axboe { 501d6d48196SJens Axboe int nr_phys_segs = bio_phys_segments(q, bio); 502d6d48196SJens Axboe 50313f05c8dSMartin K. Petersen if (req->nr_phys_segments + nr_phys_segs > queue_max_segments(q)) 50413f05c8dSMartin K. Petersen goto no_merge; 50513f05c8dSMartin K. Petersen 5064eaf99beSMartin K. Petersen if (blk_integrity_merge_bio(q, req, bio) == false) 50713f05c8dSMartin K. Petersen goto no_merge; 508d6d48196SJens Axboe 509d6d48196SJens Axboe /* 510d6d48196SJens Axboe * This will form the start of a new hw segment. Bump both 511d6d48196SJens Axboe * counters. 512d6d48196SJens Axboe */ 513d6d48196SJens Axboe req->nr_phys_segments += nr_phys_segs; 514d6d48196SJens Axboe return 1; 51513f05c8dSMartin K. Petersen 51613f05c8dSMartin K. Petersen no_merge: 517e0c72300SRitesh Harjani req_set_nomerge(q, req); 51813f05c8dSMartin K. Petersen return 0; 519d6d48196SJens Axboe } 520d6d48196SJens Axboe 521d6d48196SJens Axboe int ll_back_merge_fn(struct request_queue *q, struct request *req, 522d6d48196SJens Axboe struct bio *bio) 523d6d48196SJens Axboe { 5245e7c4274SJens Axboe if (req_gap_back_merge(req, bio)) 5255e7c4274SJens Axboe return 0; 5267f39add3SSagi Grimberg if (blk_integrity_rq(req) && 5277f39add3SSagi Grimberg integrity_req_gap_back_merge(req, bio)) 5287f39add3SSagi Grimberg return 0; 529f31dc1cdSMartin K. Petersen if (blk_rq_sectors(req) + bio_sectors(bio) > 53017007f39SDamien Le Moal blk_rq_get_max_sectors(req, blk_rq_pos(req))) { 531e0c72300SRitesh Harjani req_set_nomerge(q, req); 532d6d48196SJens Axboe return 0; 533d6d48196SJens Axboe } 5342cdf79caSJens Axboe if (!bio_flagged(req->biotail, BIO_SEG_VALID)) 535d6d48196SJens Axboe blk_recount_segments(q, req->biotail); 5362cdf79caSJens Axboe if (!bio_flagged(bio, BIO_SEG_VALID)) 537d6d48196SJens Axboe blk_recount_segments(q, bio); 538d6d48196SJens Axboe 539d6d48196SJens Axboe return ll_new_hw_segment(q, req, bio); 540d6d48196SJens Axboe } 541d6d48196SJens Axboe 542d6d48196SJens Axboe int ll_front_merge_fn(struct request_queue *q, struct request *req, 543d6d48196SJens Axboe struct bio *bio) 544d6d48196SJens Axboe { 5455e7c4274SJens Axboe 5465e7c4274SJens Axboe if (req_gap_front_merge(req, bio)) 5475e7c4274SJens Axboe return 0; 5487f39add3SSagi Grimberg if (blk_integrity_rq(req) && 5497f39add3SSagi Grimberg integrity_req_gap_front_merge(req, bio)) 5507f39add3SSagi Grimberg return 0; 551f31dc1cdSMartin K. Petersen if (blk_rq_sectors(req) + bio_sectors(bio) > 55217007f39SDamien Le Moal blk_rq_get_max_sectors(req, bio->bi_iter.bi_sector)) { 553e0c72300SRitesh Harjani req_set_nomerge(q, req); 554d6d48196SJens Axboe return 0; 555d6d48196SJens Axboe } 5562cdf79caSJens Axboe if (!bio_flagged(bio, BIO_SEG_VALID)) 557d6d48196SJens Axboe blk_recount_segments(q, bio); 5582cdf79caSJens Axboe if (!bio_flagged(req->bio, BIO_SEG_VALID)) 559d6d48196SJens Axboe blk_recount_segments(q, req->bio); 560d6d48196SJens Axboe 561d6d48196SJens Axboe return ll_new_hw_segment(q, req, bio); 562d6d48196SJens Axboe } 563d6d48196SJens Axboe 564e7e24500SJens Axboe /* 565e7e24500SJens Axboe * blk-mq uses req->special to carry normal driver per-request payload, it 566e7e24500SJens Axboe * does not indicate a prepared command that we cannot merge with. 567e7e24500SJens Axboe */ 568e7e24500SJens Axboe static bool req_no_special_merge(struct request *req) 569e7e24500SJens Axboe { 570e7e24500SJens Axboe struct request_queue *q = req->q; 571e7e24500SJens Axboe 572e7e24500SJens Axboe return !q->mq_ops && req->special; 573e7e24500SJens Axboe } 574e7e24500SJens Axboe 575d6d48196SJens Axboe static int ll_merge_requests_fn(struct request_queue *q, struct request *req, 576d6d48196SJens Axboe struct request *next) 577d6d48196SJens Axboe { 578d6d48196SJens Axboe int total_phys_segments; 57986771427SFUJITA Tomonori unsigned int seg_size = 58086771427SFUJITA Tomonori req->biotail->bi_seg_back_size + next->bio->bi_seg_front_size; 581d6d48196SJens Axboe 582d6d48196SJens Axboe /* 583d6d48196SJens Axboe * First check if the either of the requests are re-queued 584d6d48196SJens Axboe * requests. Can't merge them if they are. 585d6d48196SJens Axboe */ 586e7e24500SJens Axboe if (req_no_special_merge(req) || req_no_special_merge(next)) 587d6d48196SJens Axboe return 0; 588d6d48196SJens Axboe 5895e7c4274SJens Axboe if (req_gap_back_merge(req, next->bio)) 590854fbb9cSKeith Busch return 0; 591854fbb9cSKeith Busch 592d6d48196SJens Axboe /* 593d6d48196SJens Axboe * Will it become too large? 594d6d48196SJens Axboe */ 595f31dc1cdSMartin K. Petersen if ((blk_rq_sectors(req) + blk_rq_sectors(next)) > 59617007f39SDamien Le Moal blk_rq_get_max_sectors(req, blk_rq_pos(req))) 597d6d48196SJens Axboe return 0; 598d6d48196SJens Axboe 599d6d48196SJens Axboe total_phys_segments = req->nr_phys_segments + next->nr_phys_segments; 60086771427SFUJITA Tomonori if (blk_phys_contig_segment(q, req->biotail, next->bio)) { 60186771427SFUJITA Tomonori if (req->nr_phys_segments == 1) 60286771427SFUJITA Tomonori req->bio->bi_seg_front_size = seg_size; 60386771427SFUJITA Tomonori if (next->nr_phys_segments == 1) 60486771427SFUJITA Tomonori next->biotail->bi_seg_back_size = seg_size; 605d6d48196SJens Axboe total_phys_segments--; 60686771427SFUJITA Tomonori } 607d6d48196SJens Axboe 6088a78362cSMartin K. Petersen if (total_phys_segments > queue_max_segments(q)) 609d6d48196SJens Axboe return 0; 610d6d48196SJens Axboe 6114eaf99beSMartin K. Petersen if (blk_integrity_merge_rq(q, req, next) == false) 61213f05c8dSMartin K. Petersen return 0; 61313f05c8dSMartin K. Petersen 614d6d48196SJens Axboe /* Merge is OK... */ 615d6d48196SJens Axboe req->nr_phys_segments = total_phys_segments; 616d6d48196SJens Axboe return 1; 617d6d48196SJens Axboe } 618d6d48196SJens Axboe 61980a761fdSTejun Heo /** 62080a761fdSTejun Heo * blk_rq_set_mixed_merge - mark a request as mixed merge 62180a761fdSTejun Heo * @rq: request to mark as mixed merge 62280a761fdSTejun Heo * 62380a761fdSTejun Heo * Description: 62480a761fdSTejun Heo * @rq is about to be mixed merged. Make sure the attributes 62580a761fdSTejun Heo * which can be mixed are set in each bio and mark @rq as mixed 62680a761fdSTejun Heo * merged. 62780a761fdSTejun Heo */ 62880a761fdSTejun Heo void blk_rq_set_mixed_merge(struct request *rq) 62980a761fdSTejun Heo { 63080a761fdSTejun Heo unsigned int ff = rq->cmd_flags & REQ_FAILFAST_MASK; 63180a761fdSTejun Heo struct bio *bio; 63280a761fdSTejun Heo 633e8064021SChristoph Hellwig if (rq->rq_flags & RQF_MIXED_MERGE) 63480a761fdSTejun Heo return; 63580a761fdSTejun Heo 63680a761fdSTejun Heo /* 63780a761fdSTejun Heo * @rq will no longer represent mixable attributes for all the 63880a761fdSTejun Heo * contained bios. It will just track those of the first one. 63980a761fdSTejun Heo * Distributes the attributs to each bio. 64080a761fdSTejun Heo */ 64180a761fdSTejun Heo for (bio = rq->bio; bio; bio = bio->bi_next) { 6421eff9d32SJens Axboe WARN_ON_ONCE((bio->bi_opf & REQ_FAILFAST_MASK) && 6431eff9d32SJens Axboe (bio->bi_opf & REQ_FAILFAST_MASK) != ff); 6441eff9d32SJens Axboe bio->bi_opf |= ff; 64580a761fdSTejun Heo } 646e8064021SChristoph Hellwig rq->rq_flags |= RQF_MIXED_MERGE; 64780a761fdSTejun Heo } 64880a761fdSTejun Heo 64926308eabSJerome Marchand static void blk_account_io_merge(struct request *req) 65026308eabSJerome Marchand { 65126308eabSJerome Marchand if (blk_do_io_stat(req)) { 65226308eabSJerome Marchand struct hd_struct *part; 65326308eabSJerome Marchand int cpu; 65426308eabSJerome Marchand 65526308eabSJerome Marchand cpu = part_stat_lock(); 65609e099d4SJerome Marchand part = req->part; 65726308eabSJerome Marchand 65826308eabSJerome Marchand part_round_stats(cpu, part); 659316d315bSNikanth Karthikesan part_dec_in_flight(part, rq_data_dir(req)); 66026308eabSJerome Marchand 6616c23a968SJens Axboe hd_struct_put(part); 66226308eabSJerome Marchand part_stat_unlock(); 66326308eabSJerome Marchand } 66426308eabSJerome Marchand } 66526308eabSJerome Marchand 666d6d48196SJens Axboe /* 667b973cb7eSJens Axboe * For non-mq, this has to be called with the request spinlock acquired. 668b973cb7eSJens Axboe * For mq with scheduling, the appropriate queue wide lock should be held. 669d6d48196SJens Axboe */ 670b973cb7eSJens Axboe static struct request *attempt_merge(struct request_queue *q, 671b973cb7eSJens Axboe struct request *req, struct request *next) 672d6d48196SJens Axboe { 673d6d48196SJens Axboe if (!rq_mergeable(req) || !rq_mergeable(next)) 674b973cb7eSJens Axboe return NULL; 675d6d48196SJens Axboe 676288dab8aSChristoph Hellwig if (req_op(req) != req_op(next)) 677b973cb7eSJens Axboe return NULL; 678f31dc1cdSMartin K. Petersen 679d6d48196SJens Axboe /* 680d6d48196SJens Axboe * not contiguous 681d6d48196SJens Axboe */ 68283096ebfSTejun Heo if (blk_rq_pos(req) + blk_rq_sectors(req) != blk_rq_pos(next)) 683b973cb7eSJens Axboe return NULL; 684d6d48196SJens Axboe 685d6d48196SJens Axboe if (rq_data_dir(req) != rq_data_dir(next) 686d6d48196SJens Axboe || req->rq_disk != next->rq_disk 687e7e24500SJens Axboe || req_no_special_merge(next)) 688b973cb7eSJens Axboe return NULL; 689d6d48196SJens Axboe 6908fe0d473SMike Christie if (req_op(req) == REQ_OP_WRITE_SAME && 6914363ac7cSMartin K. Petersen !blk_write_same_mergeable(req->bio, next->bio)) 692b973cb7eSJens Axboe return NULL; 6934363ac7cSMartin K. Petersen 694d6d48196SJens Axboe /* 695d6d48196SJens Axboe * If we are allowed to merge, then append bio list 696d6d48196SJens Axboe * from next to rq and release next. merge_requests_fn 697d6d48196SJens Axboe * will have updated segment counts, update sector 698d6d48196SJens Axboe * counts here. 699d6d48196SJens Axboe */ 700d6d48196SJens Axboe if (!ll_merge_requests_fn(q, req, next)) 701b973cb7eSJens Axboe return NULL; 702d6d48196SJens Axboe 703d6d48196SJens Axboe /* 70480a761fdSTejun Heo * If failfast settings disagree or any of the two is already 70580a761fdSTejun Heo * a mixed merge, mark both as mixed before proceeding. This 70680a761fdSTejun Heo * makes sure that all involved bios have mixable attributes 70780a761fdSTejun Heo * set properly. 70880a761fdSTejun Heo */ 709e8064021SChristoph Hellwig if (((req->rq_flags | next->rq_flags) & RQF_MIXED_MERGE) || 71080a761fdSTejun Heo (req->cmd_flags & REQ_FAILFAST_MASK) != 71180a761fdSTejun Heo (next->cmd_flags & REQ_FAILFAST_MASK)) { 71280a761fdSTejun Heo blk_rq_set_mixed_merge(req); 71380a761fdSTejun Heo blk_rq_set_mixed_merge(next); 71480a761fdSTejun Heo } 71580a761fdSTejun Heo 71680a761fdSTejun Heo /* 717d6d48196SJens Axboe * At this point we have either done a back merge 718d6d48196SJens Axboe * or front merge. We need the smaller start_time of 719d6d48196SJens Axboe * the merged requests to be the current request 720d6d48196SJens Axboe * for accounting purposes. 721d6d48196SJens Axboe */ 722d6d48196SJens Axboe if (time_after(req->start_time, next->start_time)) 723d6d48196SJens Axboe req->start_time = next->start_time; 724d6d48196SJens Axboe 725d6d48196SJens Axboe req->biotail->bi_next = next->bio; 726d6d48196SJens Axboe req->biotail = next->biotail; 727d6d48196SJens Axboe 728a2dec7b3STejun Heo req->__data_len += blk_rq_bytes(next); 729d6d48196SJens Axboe 730d6d48196SJens Axboe elv_merge_requests(q, req, next); 731d6d48196SJens Axboe 73242dad764SJerome Marchand /* 73342dad764SJerome Marchand * 'next' is going away, so update stats accordingly 73442dad764SJerome Marchand */ 73542dad764SJerome Marchand blk_account_io_merge(next); 736d6d48196SJens Axboe 737d6d48196SJens Axboe req->ioprio = ioprio_best(req->ioprio, next->ioprio); 738ab780f1eSJens Axboe if (blk_rq_cpu_valid(next)) 739ab780f1eSJens Axboe req->cpu = next->cpu; 740d6d48196SJens Axboe 741e4d750c9SJens Axboe /* 742e4d750c9SJens Axboe * ownership of bio passed from next to req, return 'next' for 743e4d750c9SJens Axboe * the caller to free 744e4d750c9SJens Axboe */ 7451cd96c24SBoaz Harrosh next->bio = NULL; 746b973cb7eSJens Axboe return next; 747d6d48196SJens Axboe } 748d6d48196SJens Axboe 749b973cb7eSJens Axboe struct request *attempt_back_merge(struct request_queue *q, struct request *rq) 750d6d48196SJens Axboe { 751d6d48196SJens Axboe struct request *next = elv_latter_request(q, rq); 752d6d48196SJens Axboe 753d6d48196SJens Axboe if (next) 754d6d48196SJens Axboe return attempt_merge(q, rq, next); 755d6d48196SJens Axboe 756b973cb7eSJens Axboe return NULL; 757d6d48196SJens Axboe } 758d6d48196SJens Axboe 759b973cb7eSJens Axboe struct request *attempt_front_merge(struct request_queue *q, struct request *rq) 760d6d48196SJens Axboe { 761d6d48196SJens Axboe struct request *prev = elv_former_request(q, rq); 762d6d48196SJens Axboe 763d6d48196SJens Axboe if (prev) 764d6d48196SJens Axboe return attempt_merge(q, prev, rq); 765d6d48196SJens Axboe 766b973cb7eSJens Axboe return NULL; 767d6d48196SJens Axboe } 7685e84ea3aSJens Axboe 7695e84ea3aSJens Axboe int blk_attempt_req_merge(struct request_queue *q, struct request *rq, 7705e84ea3aSJens Axboe struct request *next) 7715e84ea3aSJens Axboe { 77272ef799bSTahsin Erdogan struct elevator_queue *e = q->elevator; 773e4d750c9SJens Axboe struct request *free; 77472ef799bSTahsin Erdogan 775bd166ef1SJens Axboe if (!e->uses_mq && e->type->ops.sq.elevator_allow_rq_merge_fn) 776c51ca6cfSJens Axboe if (!e->type->ops.sq.elevator_allow_rq_merge_fn(q, rq, next)) 77772ef799bSTahsin Erdogan return 0; 77872ef799bSTahsin Erdogan 779e4d750c9SJens Axboe free = attempt_merge(q, rq, next); 780e4d750c9SJens Axboe if (free) { 781e4d750c9SJens Axboe __blk_put_request(q, free); 782e4d750c9SJens Axboe return 1; 783e4d750c9SJens Axboe } 784e4d750c9SJens Axboe 785e4d750c9SJens Axboe return 0; 7865e84ea3aSJens Axboe } 787050c8ea8STejun Heo 788050c8ea8STejun Heo bool blk_rq_merge_ok(struct request *rq, struct bio *bio) 789050c8ea8STejun Heo { 790e2a60da7SMartin K. Petersen if (!rq_mergeable(rq) || !bio_mergeable(bio)) 791050c8ea8STejun Heo return false; 792050c8ea8STejun Heo 793288dab8aSChristoph Hellwig if (req_op(rq) != bio_op(bio)) 794f31dc1cdSMartin K. Petersen return false; 795f31dc1cdSMartin K. Petersen 796050c8ea8STejun Heo /* different data direction or already started, don't merge */ 797050c8ea8STejun Heo if (bio_data_dir(bio) != rq_data_dir(rq)) 798050c8ea8STejun Heo return false; 799050c8ea8STejun Heo 800050c8ea8STejun Heo /* must be same device and not a special request */ 801e7e24500SJens Axboe if (rq->rq_disk != bio->bi_bdev->bd_disk || req_no_special_merge(rq)) 802050c8ea8STejun Heo return false; 803050c8ea8STejun Heo 804050c8ea8STejun Heo /* only merge integrity protected bio into ditto rq */ 8054eaf99beSMartin K. Petersen if (blk_integrity_merge_bio(rq->q, rq, bio) == false) 806050c8ea8STejun Heo return false; 807050c8ea8STejun Heo 8084363ac7cSMartin K. Petersen /* must be using the same buffer */ 8098fe0d473SMike Christie if (req_op(rq) == REQ_OP_WRITE_SAME && 8104363ac7cSMartin K. Petersen !blk_write_same_mergeable(rq->bio, bio)) 8114363ac7cSMartin K. Petersen return false; 8124363ac7cSMartin K. Petersen 813050c8ea8STejun Heo return true; 814050c8ea8STejun Heo } 815050c8ea8STejun Heo 81634fe7c05SChristoph Hellwig enum elv_merge blk_try_merge(struct request *rq, struct bio *bio) 817050c8ea8STejun Heo { 8181e739730SChristoph Hellwig if (req_op(rq) == REQ_OP_DISCARD && 8191e739730SChristoph Hellwig queue_max_discard_segments(rq->q) > 1) 8201e739730SChristoph Hellwig return ELEVATOR_DISCARD_MERGE; 8211e739730SChristoph Hellwig else if (blk_rq_pos(rq) + blk_rq_sectors(rq) == bio->bi_iter.bi_sector) 822050c8ea8STejun Heo return ELEVATOR_BACK_MERGE; 8234f024f37SKent Overstreet else if (blk_rq_pos(rq) - bio_sectors(bio) == bio->bi_iter.bi_sector) 824050c8ea8STejun Heo return ELEVATOR_FRONT_MERGE; 825050c8ea8STejun Heo return ELEVATOR_NO_MERGE; 826050c8ea8STejun Heo } 827